Many conventional telephone communication systems incorporate visual display capabilities which allow information to be displayed. Prior art devices include: telephones with liquid crystal displays (LCDs) mounted on the telephone base or in the handset; wall-mounted pay telephones with built-in cathode ray tube (CRT) displays and computerized communication systems which combine a telephone with a modem or other communication device.
At the present time the use of such display devices is either limited to the display of small amounts of information such as dialed numbers, names, memoranda and low-resolution graphic data or confined to "desk-top" size units with conventional full-sized displays. However, with the conversion of the existing voice grade telephone network to a network which can transmit both voice signals and data signals, the need will increase for relatively high-resolution visual displays at the telephone to display the large amount of transmitted data.
For certain applications, such as business offices, a conventional CRT or large-size, flat-panel LCD display may be integrated into the telephone base in order to provide the capability of rapidly displaying large amounts of data. In other situations, however, restricted space will not allow use of a "full-size" data display. For example, telephones designed for home use, mobile telephones, and wall-mounted telephones are generally designed to minimize side and thus could not easily incorporate a conventional size CRT display.
Even if there is space for conventional displays, the relatively high cost of a conventional high-resolution display, such as a full-size flat-panel LCD, make the use of such displays undesirable in applications where the need to display data is occasional. For example, office or factory extension telephones and pay telephones generally are used so infreguently for data display that the cost of equipping such telephones with conventional full-size displays would be unecomonical. Although these telephones could be economically equipped with conventional one or two line LCD displays these latter displays can only display a small amount of alphanumeric data.
In order to overcome the present limitations of full-size visual displays, some well-known techniques have been used to "enlarge" small displays and make them easier to view. Normally, a visible real image can be no larger than the physical display enclosure. However, it is possible to create an enlarged image by magnifying the real image produced by a small conventional display. This technique is presently used in the viewfinders of some conventional video cameras. Although this technique could be applied to telephone displays, a problem with this approach is that the magnification does not significantly increase the resolution of the initial display, it merely makes the small display easier to see. Thus, with a conventional display generated on a small CRT, the resolution of the initial image and, consequently, the resolution of the magnified image is not high enough to adequately display a full page of text or to display graphics information. It is possible to use a high-resolution CRT to generate the initial image. Conventional miniature CRTs exist which are capable of displaying a full page of text or graphics, but these CRTs are expensive and have the normal drawbacks associated with CRTs such as power supply problems and reliability.
Consequently, the relationship of case size to image size has meant that only very small displays could be incorporated into the limited space available in telephone handsets. A further problem with conventional displays is that they generally require that the user hold the handset at a comfortable reading distance to view the display whereas the user must place the handset near his ear to use the telephone. Thus, it is not possible to simultaneously use the telephone and view the display.
Accordingly, it is an object of the present invention to provide a telephone handset which has the ability to display a full page of text or graphics information.
It is another object of the present invention to provide a telephone handset which incorporates the ability to display a full page of text or graphics information without physically increasing the size of the telephone.
It is another object of the present invention to provide a telephone handset in which a full-page display can be viewed while simultaneously speaking and listening on the telephone.
It is still another object of the present invention to provide a telephone handset which incorporates a high-resolution visual display which is compact and space-efficient.
It is yet another object of the present invention to provide a telephone handset which incorporates a high-resolution visual display on which displayed data can only be seen by user of the telephone.